Selective dispensing apparatus having door interlock structure

ABSTRACT

An electromechanical control system for the product selection doors of a multiple-section, product-display vending machine locks the doors closed until a proper coinage deposit has been made, whereupon a selected door may be opened to remove a product from the machine. After opening, the door is automatically held against accidental closing, although manual closing of the open door is permitted after the purchased product is removed. If the open door is not manually closed, a timer associated with the system causes automatic closing of the door after a predetermined period of time has elapsed. The product conveyor of the machine may not be advanced while the door remains open, and any attempt to actuate the conveyor initiates automatic closing of the door.

[ Aug. 14, 1973 SELECTIVE DISPENSING APPARATUS HAVING DOOR INTERLOCK STRUCTURE Wilbert 0. ONeal, lndependence, Mo.

Assignee: The Vendo Company, Kansas City,

Filed: Mar. 30, 1972 Appl. No.: 239,541

{75] Inventor:

References Cited UNITED STATES PATENTS 2,875,878 3/1959 Hoban 312/97 X 3,147,838 9/1964 Mueller et a1. 312/97 X 3,697,148 10/1972 Weber 312/138 R Primad Examiner-James c. Mitchell Attorney-Schmidt, Johnson, l-lovey & Williams ABSTRACT An electromechanical control system for the product selection doors of a multiple-section, product-display vending machine locks the doors closed until a proper coinage deposit has been made, whereupon a selected door may be opened to remove a product from the machine. After opening, the door is automatically held against accidental closing, although manual closing of the open door is permitted after the purchased product is removed. if the open door is not manually closed, a timer associated with the system causes automatic closing of the door after a predetermined period of time has elapsed. The product conveyor of the machine may not be advanced while the door remains open, and any attempt to actuate the conveyor initiates automatic closing of the door.

11 Claims, 13 Drawing Figures SELECTIVE DISPENSING APPARATUS HAVING DOOR INTERLOCK STRUCTURE This invention relates to an electromechanical control system for regulating the product compartment access doors of vending stations in a multipurpose selective vending machine.

The electromechanical system of the present invention has particularutility in shopping type vending machines which display a large assortment of various food products to a potential customer and allow him to advance a product conveyor behind the display window of the machine until the conveyor bin containing the selected product is brought into position behind a vending station access door. After deposit of a proper combination of coinage, the doors are unlocked and the customer is permitted to open the proper door to remove his selection.

An important object of the present invention is to provide an access door control system for multipurpose selective vending machines as above described which locks the access doors against opening thereof until proper credit has been deposited in the machine and, after opening of a door, holds the latter against other than intentional closing thereof such that a customer, if he so desires, may use only one hand to deposit his credit, open the door, and remove his selection.

A further important object of the present invention is the provision of a control system as aforesaid which allows a customer who is accustomed to closing vending doors after removing a purchase from the machine to override the structure holding the door open and manually close the door.

Another important object of the present invention is to provide a control system as above set forth wherein an open door is automatically closed aftera preselected period of time has elapsed, in the event that the door has not been manually closed.

Yet another important object of the instant invention is to provide a control system having all of the advantages as aforesaid, with the additional feature of providing for immediate, automatic closing of an open door when an attempt is made to jackpot the machine by actuating the product conveyor to bring additional products to the open door.

Other important objects will be made clear or become apparent from the following specification and accompanying drawings, wherein:

FIG. I is a fragmentary, elevational view of the control system of the present invention mounted on the inside surface of a vending machine cabinet door, one of the product access doors having the open position thereof indicated in phantom;

FIG. 2 is a vertical, cross-sectional view of the system taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged, fragmentary, vertical crosssectional view of one of the access doors and accompanying mounting structure therefor;

FIG. 4 is an enlarged, fragmentary, horizontal, crosssectional view of structure for holding one of the doors in an open condition, taken along line 4-4 of FIG. 1;

FIG. 5 is an enlarged, fragmentary, horizontal, crosssectional view of the locking means for one of the doors taken along line 5-5 of FIG. 1;

FIG. 6 is a front perspective view, on a reduced scale, of a shopping" type vending machine for which the control system of the present invention has particular utility;

FIGS. 7-12 are diagrammatic representations illustrating the operation of the control system, all looking toward the interior of the cabinet from the inner door thereof, except for FIG. 1 l which views the control system from the opposite direction; and

FIG. 13 is a schematic diagram of a simplified, representative control circuit for the door timer and product conveyor mechanism.

Referring initially to FIG. 6, the vending machine depicted therein has a cabinet 20 provided with an outer, decorative door 22 having a large, rectangular opening 24. A plurality of horizontally aligned vending stations 26 are situated along the lower stretch of a similar rectangular opening 28 of the inner, storage compartment door 40 of cabinet 20, and a slightly inclined display window 32, above the line of vending stations 26 within opening 28, permits viewing of food products or the like stored in bins of an endless product conveyor 34. A switch button on outer door 22 controls energization of conveyor 34 to permit a potential customer to shop by depressing button 35 to advance the products vertically behind window 32 until the row containing his selection appears at stations 26. After depositing the proper coinage, the customer is allowed to open any one of the series of transparent access doors 36 at stations 26 to remove his selection.

A space between outer door 22 and inner door 30 below openings 24 and 28 is adapted to house coinage control mechanism which is designed, for example, to check the amount of credit deposited inthe machine, perform authenticity checks, and return change to the customer when needed. This mechanism, as well as details of the product conveyor 34, form no part of the present invention and, accordingly, will not be hereinafter described, although frequent reference will be made thereto in order to describe the control system of the present invention in the clearest manner possible.

As shown most clearly in FIGS. 1-3, the components of the control system embodying the concepts of the present invention are mounted on a large, rectangular main plate 38 which, in turn, is mounted on the inner face of inner door 30. Plate 38 has an uppennost, horizontal flange 40 which overlies the lower margin of opening 28 in inner door 30 and a pair of slightly horizontally offset, upper and lower planar mounting sec tions 42 and 44 respectively. A door frame 45 affixed to the upper end of section 42 has a series of horizontally spaced, vertically extending guides 450 which overlap the side margins of adjacent doors 36 to confine the latter during vertical shifting thereof and to define adjacent access openings which the doors 36 serve to open and close.

The access doors 36, preferably being of various sizes corresponding to the spacing between guides 45a, are identical in construction and operation. Accordingly, for purposes of simplification, only the details of one of the doors 36 will be described, with the understanding that its principles are equally applicable to the other doors 36. Door 36 is mounted for individual, vertical shifting movement on upper section 42 by means of an elongated, vertical bar extension 46 which is secured at the uppermost end thereof to the lower end of door 36 by a pin and washer assembly 48 (FIG. 3). The bar 46 is disposed on the opposite side of section 42 from door 36 and projects through an opening 50 in the horizontal stretch 52 (FIG. 2) of plate 38 interconnecting sections 42 and 44. A vertically disposed T-slot 54 in section 42 receives the pin of assembly 48 for shifting of door 36 and bar 46 as a unit between the two extreme positions illustrated by the second door from the left in FIG. 1. A bending coiled spring 56 interconnects door 36 and the lower extremity of section 42 to yieldably bias door 36 toward its closed condition, and a manual operating ledge 58 at the uppermost end of door 36 abuts flange 40 when door 36 is depressed to its fullest extent.

Each door 36 is provided with a releasable locking means, broadly denoted by the numeral 60 (FIGS. 1, 2

and which prevents opening of the corresponding door 36 until the proper coinage combination has been deposited. Locking means 60 includes a locking cylinder 62 which is supported by an L-shaped bracket 64 on plate section 44 for rotation about an axis perpendicular to the surface of section 44. Cylinder 62 coopcrates with a generally crescent-shaped inlet 68 (FIG. 7) in bar 46 adjacent the lower end of one side thereof to block or permit passage of bar 46 through a notch 66, depending upon a rotative position of notch 66 in cylinder 62.

A cylinder crank'70 secured to the outer end of cylinder 62 is spring-loaded to bias cylinder 62 into the locking position thereof wherein passage of bar 46 through notch 66 is denied, and a solenoid 72, adjacent the lower margin of plate section 44 operates through linkage 74 to rotate crank 70 and hence lock-cylinder 62. Lock solenoid 72 is adapted to be connected to a source of electrical power (not shown) for energization and a switch 76 adjacent the opposite side of vertical bar 46 is interposed between the source of power and lock solenoid 72 for controlling actuation of the latter. Switch 76, in turn, is made responsive to vertical shifting of vertical bar 46 by a tab 78 on bar 46 which shifts the spring-loaded switch lever 80 between alternate positions opening and closing switch 76.

It is contemplated that solenoid 72 be electrically coupled with credit checking mechanism for evaluating the coinage deposited by a customer and that, upon deposit of the proper credit, power be supplied to the circuit of which switch 76 and solenoid 72 are components. In FIG. 1, switch lever 80 is disposed to maintain switch 76 in an open condition such that, even though a proper coinage deposit has been made, solenoid 72 remains unactuated until such time as the door 36 is depressed slightly to correspondingly shift tab 78 a sufficient distance to allow lever 80 to spring out of its switch-opening position. A door interlock system, which prevents opening more than one door at a time, forms no part of the present invention but includes an electrical circuit of which the series of switches 82 along the lower margin of main plate 38 are components.

When a door 36 is opened, it is retained in this condition by control structure on section 44, broadly denoted by the numeral 84, and shown in detail in FIGS. 1, 2 and 4. Control structure 84 includes a U-shaped, horizontally extending bar 86 which traverses vertical bars 46 in front of the latter and is supported for horizontal shifting movement by virtue of a pair of spaced support posts 88 projecting slots 90 in bar 86 (FIG. 1). A light tension spring 92 at the right end of bar 86 (FIG. 1) yieldably biases bar 86 to its rightmost position as shown therein. A plurality of identical, springloaded pawls 94 (FIGS. 4 and 7-12) are spaced along bar 86 to serve as latches for the doors 36, respectively, there being one pawl 94 for each door 36. Each pawl 94 is pivotally mounted on the inner vertical face of common bar 86 for swinging about a pivot pin 96 which defines an axis perpendicular to bar 86. A torsion spring 98 interconnecting pin 96 within the bight of bar 86 and pawl 94 yieldably biases pawl 94 into a normal, horizontal disposition.

Each vertical bar 46 is provided with an elongated, vertically extending rack 100 along the left side thereof, viewing FIGS. 1 and 11, which presents a series of notches for latchingly receiving the outermost tip of the corresponding pawl 94 when the corresponding door 36 has been depressed to a sufficient extent. A spring-loaded anti-backup pawl 102 on section 44 above bar 86 is provided for the doors 36 adjacent the right side of each vertical bar 46 (viewing FIGS. 1 and 11), respectively, for positive engagement with an antibackup rack 104 extending along the right side of the corresponding vertical bar 46.

The common bar 86 is shiftable between three horizontal positions, the first of such positions being illustrated in FIG. 1 wherein components of the system are in a standby condition with doors 36 closed. A second position of bar 86 is slightly to the left of the FIG. 1 position thereof wherein a spring-loaded, L-shaped biasing member 106 pivotally mounted on section 42 adjacent the right end of bar 86 engages a cross pin 108 through the bar 86 to increase the resistance to further leftward shifting of bar 86. A stretegically located roller 110 (FIG. 7) on bar 86 for each door 36, is disposed for engagement by an inclined cam surface 112 on the corresponding vertical bar 46 to effect such initial shifting of the common bar 86. A third position of bar 86 (FIG. 11) is to the extreme left of the original position depicted in FIG. 1 and is effected by actuation of shifter mechanism 114 which includes an electrically actuatable solenoid 116, a J-shaped rod 118, and a pivotal arm which engages a roller 122 at the leftmost end of bar 86.

FIG. 13 shows a simplified circuit diagram for controlling the motor 124 of a timer and motor 126 of the product conveyor 34 with respect to the other components of the control system. Operating voltage for the components of the circuit is supplied by a pair of lines 128 and 130. A single-pole double throw switch 132 disposed below common bar 86 (FIG. 1) and responsive to shifting of the latter, is shiftable between a pair of opposed terminals 134 and 136 and is shown in FIG. 13 with common bar 86 in its standby position with all of the doors 36 closed. A lead 138 connects terminal 134 with one side of the timer motor 124, and a lead 140 interconnects the opposite side of timer motor 124 and line 130. A single-pole, single-throw switch 142 operated by the timer motor 124 is interposed between a lead 144 from lead 138 and lead 146 from one side of the shifter solenoid 116. Another lead 148 interconnects the opposite side of solenoid 116 and line 130. A pair of leads 150 and 152 from terminal 136 and lead 138 respectively, are connected to shopping button switch 35 on outer door 22 which is a double-pole, double-throw switch. A lead 154 interconnects one of the terminals 156 of switch 35 with lead 146 from one side of solenoid 116, while another lead 158 interconnects the other terminal 160 of switch 35 with one side of the conveyor motor 126. A short lead 162 connects the opposite side of motor 126 with line 130.

OPERATION The operation ofthe control system may be most easily understood by frequent reference to FIGS. 7-12 showing the components of the control system in various stages of operation. Prior to operation of the machine, all of the access doors 36 are in their closed conditions, presenting the potential customer with the arrangement depicted in FIG. 6. The conveyor 34 may be advanced as required by pressing switch 35 to bring products successively to stations 26, but doors 36 may not be opened until the proper coin combination has been deposited. FIG. 7 shows the condition of the vertical bar 46 of a representative door 36 and related structure at this time, with the notch 66 of locking cylinder 62 disposed to deny passage of bar 46 therethrough thus locking the corresponding door 36 against opening, and the antibackup pawl 102, along with latching pawl 94, both in standby conditions.

It is important to note that because inlet 68 on bar 46 is substantially larger than the diameter of lock cylinder 62, the bar 46 is permitted slight initial downward movement until such time as the upper end of inlet 68 strikes the body of cylinder 62. This initial free travel is sufficient to move tab 78 away from switch lever 80 to close switch 76. Thus, when a customer has deposited his coinage, credit and authenticity checks are immediately performed by other components of the vending machine and, if the results are satisfactory, electrical power is supplied to the circuit containing switch 76 and lock solenoid 72. When the customer makes his selection and depresses the appropriate door 36, switch 76 closes to actuate lock solenoid 72 which rotates lock cylinder 62 via linkage 74 and crank 70 into the position illustrated by the right-hand lock cylinder 62 in FIG. 8, thus permitting opening pfthe chosen door 36 to continue as the vertical bar 46 thereof passes through notch 66.

As the vertical bar 46 continues downwardly, the cam surface 112 thereof engages roller 110 on common bar 86 to effect slight lateral shifting of common bar 86. During such initial shifting, the lock solenoid 72 is de-energized to permit linkage 74 to drop back to its normal, unactuated position by virtue of the enlarged linkage opening 74a, the crank 70 remaining in its rotated position during such return of linkage 74. The initial lateral shifting of common bar 86 also places. the latching pawl 94 into proper disposition below rack 100 for subsequent engagement thereby, as shown in FIG. 8.

During the time that roller 110 engages cam surface 112, the anti-backup pawl 102 engages the proximal rack 104 and swings downwardly for successive reception into each notch in the rack 104 as door 36 continues to be depressed. This assures that credit deposited by a customer will not be lost, even if the customer's hand should slip from door 36 during depression of the latter.

As door 36 continues to be opened against the bias of return spring 56, the vertical bar 46 moves from its FIG. 8 position to that of FIG. 9, during which time the latching pawl 94 is engaged and swung downwardly by the proximal rack 100 as the outer tip of pawl 94 is successively received within successive notches of rack 100. Once pawl 94 has latchingly engaged rack 100, rack 104 moves past anti-backup pawl 102 such that door 36 is retained against closing after this time only by the latching pawl 94. The return spring 56 continuously seeks to override the efforts of pawl 94 during this time to shift door 36 back to its closed condition. However, because of the additional resistance provided by the spring-loaded member 106, the common bar 86 is yieldably prevented from further lateral shifting, which would, of course, permit pawl 94 to disengage from rack 100. Thus, the door 36 is yieldably maintained in its fully open condition, permitting access to the product at the corresponding station 26 for removal from the vending machine.

At this functure, any of three possible events may occur. First, the customer may be in the habit of closing product access doors himself and, therefore, seeks to do the same with open door 36. Such action is accommodated in the present system since, when the customer grasps the door ledge 58 to raise the latter to its closed condition, the force generated through vertical bar 46 is imparted to pawl 94, and the biasing member 106 is overridden as the common bar 86 is shifted to its fullest extent as illustrated in FIG. 10. This allows pawl 94 to flip over center as shown in FIG. 12, whereupon return spring 56 aids the manual closing. Thus, door 36 may be completely manually returned to its original closed condition, whereupon the locking cylinder 62 returns to its locking condition and the remaining components resume their initial respective conditions.

A second possibility is that the customer will leave door 36 open after removing his selection. Obviously, this is an undesirable condition, and hence the provi sion of automatic closing of door 36 after sufficient time has passed to assure removal of the selected product. Such automatic closing of the door 36 is effected by virtue of a timer, the motor 124 of which is shown as a component of the simplified electrical circuit in FIG. 13, and its relationship with the door shifter mechanism 114. As door 36 is opened, the common bar 36 moves switch 132 against terminal 134, thereby energizing the timing motor 124. After a predetermined period of time has expired, such as approximately 10 seconds, the motor 124 operates to close switch 142, thus energizing shifter solenoid 116 to operate arm 120, as shown in FIGS. 10 and 11, which shifts the common bar 86 to its fullest lateral extent. Because of the relative lateral displacement of rack and the tip of pawl 94, the latter can no longer retain vertical bar 46 against the action of return spring 56, and the latter returns door 36 to its closed condition as pawls 94 and 102 swing over center as shown in FIG. 12.

The third possibility is that the customer will attempt to jackpot the machine by energizing conveyor 34 while door 36 is open to present successive products to the open vending station 26. Such action is made impossible by virtue of the circuit in FIG. 13 wherein it may be seen that when a door 36 is open, the switch 132 is forced by common bar 86 to contact terminal 134, thus bypassing conveyor motor 126, even when the shopping switch 3Sis depressed against terminal 160. Moreover, such actuation of shopping switch 35 also causes the latter to contact terminal 156, thereby causing energization of shifter solenoid 116 to effect immediate closing of the open door. Once the open door is closed, switch 132 returns to contact terminal 136, permitting actuation of conveyor 34 by shopper switch 35. The vending machine is thus once again in condition for customer use.

It is important to note that the vending process may be carried out using only one hand. After the customer has deposited his credit, he may depress the appropriate door 36 and remove hisselection with the same hand because door 36 is held openfor him. From then on, he may either manually close the door 36 or allow it to be automatically closed after i seconds or another suitable time period has elapsed.

It should be apparent to those skilled in the art that various minor modifications and substitution of equivalents could be made from the preferred structure described for purposes of illustration without departing from the spirit and gist of the invention. Accordingly, the invention should be deemed limited only by the fair scope of the claims that follow.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. in a vending machine:

means including a cabinet presenting a plurality of vending stations;

means for supplying products to each of said stations;

a shiftable product selection door for each of said stations respectively,

each door being shiftable between an open condition wherein the door permits access to a product supplied to the corresponding station and a closed condition wherein the door precludes access to said product;

first control means operably associated with said doors for releasably retaining each door respectively in the closed condition thereof;

second control means operably associated with said doors for releasably holding thedoor of a selected station in the open condition thereof after release of said first control means and shifting of the door to said condition; and

means operably coupled with each of said doors, re-

spectively, for returning an open door to the closed condition thereof upon release of said second control means.

2. The invention as claimed in claim 1, wherein said first control means includes shiftable locking means for each door, respectively, movable between a locking position wherein the locking means blocks movement of the door to the open condition thereof and an unlocking position wherein the locking means clears the door to permit such movement; electrically actuatable operating means coupled with said locking means to effect shifting of the latter from the locking to the unlocking position thereof and adapted to be connected to a source of electrical power; and switch means associated with said operating means for controlling actuation of the latter, said locking means when in the locking position thereof being disposed to permit slight initial movement of the door toward the open condition thereof, said switch means being open when the door is in its closed condition and being responsive to such initial movement of the door to close and thereby permit actuation of the operating means by said power source.

3. The invention as claimed in claim 2, wherein said locking means for each door is pivotally supported for rotation thereof between said locking and unlocking positions within the path of travel of the corresponding door, said locking means having a clearance slot therein aligned with the door when the locking means is rotated to the unlocking position thereof whereby to permit passage of the door through the slot and out of alignment with the door when the locking means is rotated to the locking position thereof whereby to deny such passage.

4. The invention as claimed in claim 1, wherein said second control means includes a control member shiftably supported for movement between first and second positions thereof along a line traversing the paths of travel of said doors and having a plurality of individual door latches thereon corresponding in number to the number of doors provided at said stations, each of said latches being disposed when said member is in the first position thereof for latchingly engaging a corresponding door when the latter is shifted to the open condition thereof and being disposed for releasing a corresponding, previously opened door when said member is in said second position thereof.

5. The invention as claimed in claim 4, wherein each latch is pivotally supported on said member for swinging of the latch by a corresponding door between a pair of alternate extreme positions as the door is moved between'said opened and said closed condition thereof.

6. The invention as claimed in claim 5, and wherein is provided yieldable means interconnecting the member and each latch respectively for biasing the latter toward a normal, standby position disposed between said alternate extreme positions thereof.

7. The invention as claimed in claim 4, and wherein is provided yieldable means coupled with said member for biasing the latter to said first position thereof.

8. The invention as claimed in claim 7, wherein said door returning means includes yieldable means biasing each door respectively toward its closed condition.

9. The invention as claimed in claim 4, and wherein is provided adjustable shifter means operable upon actuation thereof to shift said member from said first to said second position thereof.

10. The invention as claimed in claim 9, and wherein is provided timing means operably associated with said doors and said shifter means, said timing means being operable to actuate said shifter means after any one of said doors has remained in the open condition thereof for a predetermined period of time.

11. The invention as claimed in claim 9, wherein said product supplying means includes customer-actuated mechanism capable of presenting a succession of products to said stations upon customer demand, and wherein is provided means operably coupled with said shifter means for actuating the latter in response to attempted operation of said mechanism when a door is in the open condition thereof.

* l I i 

1. In a vending machine: means including a cabinet presenting a plurality of vending stations; means for supplying products to each of said stations; a shiftable product selection door for each of said stations respectively, each door being shiftable between an open condition wherein the door permits access to a product supplied to the corresponding station and a closed condition wherein the door precludes access to said product; first control means operably associated with said doors for releasably retaining each door respectively in the closed condition thereof; second control means operably associated with said doors for releasably holding the door of a selected station in the open condition thereof after release of said first control means and shifting of the door to said condition; and means operably coupled with each of said doors, respectively, for returning an open door to the closed condition thereof upon release of said second control means.
 2. The invention as claimed in claim 1, wherein said first control means includeS shiftable locking means for each door, respectively, movable between a locking position wherein the locking means blocks movement of the door to the open condition thereof and an unlocking position wherein the locking means clears the door to permit such movement; electrically actuatable operating means coupled with said locking means to effect shifting of the latter from the locking to the unlocking position thereof and adapted to be connected to a source of electrical power; and switch means associated with said operating means for controlling actuation of the latter, said locking means when in the locking position thereof being disposed to permit slight initial movement of the door toward the open condition thereof, said switch means being open when the door is in its closed condition and being responsive to such initial movement of the door to close and thereby permit actuation of the operating means by said power source.
 3. The invention as claimed in claim 2, wherein said locking means for each door is pivotally supported for rotation thereof between said locking and unlocking positions within the path of travel of the corresponding door, said locking means having a clearance slot therein aligned with the door when the locking means is rotated to the unlocking position thereof whereby to permit passage of the door through the slot and out of alignment with the door when the locking means is rotated to the locking position thereof whereby to deny such passage.
 4. The invention as claimed in claim 1, wherein said second control means includes a control member shiftably supported for movement between first and second positions thereof along a line traversing the paths of travel of said doors and having a plurality of individual door latches thereon corresponding in number to the number of doors provided at said stations, each of said latches being disposed when said member is in the first position thereof for latchingly engaging a corresponding door when the latter is shifted to the open condition thereof and being disposed for releasing a corresponding, previously opened door when said member is in said second position thereof.
 5. The invention as claimed in claim 4, wherein each latch is pivotally supported on said member for swinging of the latch by a corresponding door between a pair of alternate extreme positions as the door is moved between said opened and said closed condition thereof.
 6. The invention as claimed in claim 5, and wherein is provided yieldable means interconnecting the member and each latch respectively for biasing the latter toward a normal, standby position disposed between said alternate extreme positions thereof.
 7. The invention as claimed in claim 4, and wherein is provided yieldable means coupled with said member for biasing the latter to said first position thereof.
 8. The invention as claimed in claim 7, wherein said door returning means includes yieldable means biasing each door respectively toward its closed condition.
 9. The invention as claimed in claim 4, and wherein is provided adjustable shifter means operable upon actuation thereof to shift said member from said first to said second position thereof.
 10. The invention as claimed in claim 9, and wherein is provided timing means operably associated with said doors and said shifter means, said timing means being operable to actuate said shifter means after any one of said doors has remained in the open condition thereof for a predetermined period of time.
 11. The invention as claimed in claim 9, wherein said product supplying means includes customer-actuated mechanism capable of presenting a succession of products to said stations upon customer demand, and wherein is provided means operably coupled with said shifter means for actuating the latter in response to attempted operation of said mechanism when a door is in the open condition thereof. 